Method of dewaxing petroleum stock



Patented Sept. 8, 1936 1 1 UNITED STATES PATENT oFFIcE Leo D. Jones,Philadelphia, Pa., assignor to The Sharples Specialty Company,Philadelphia, Pa., a corporation of Delaware N0 Drawing.

10 Claims.

The present invention is a continuation in part of application SerialNo. 720,073, filed April 11, 1934, and relates to the art of removingwax from wax-containing mineral oil stock, such as residues, distillatesand solvent extracted stocks and its object has been to provide asolvent adapted to effect the selective separation of oil from wax morethoroughly under economical conditions of operation than has beenpossible in the practice of the prior art. To this end the inventioncomprises the discovery of a new selective solvent adapted for use inconnection with dewaxing operations, such solvent being cheap to produceand presenting the advantages of a more complete 'removal of wax fromoil and a smaller loss of oil in the wax than can be attained by the useof solvents heretofore commercially applied for this purpose. I

The invention consists in the discovery that icertain compounds believedto be dichlor butanes possess important advantages when used in theextraction of wax from oil. For example, a compound having the empiricalformula of C4I-IaC12 is especially useful in this connection and can beused in the separation of both crystalline, amorphous and intermediatewaxes from oil, the physical operation of removing the wax from thestock being accomplished by selective solution of the liquid hydrocarbonwith wax particles suspended therein and removal of the wax particlesfrom the solution by centrifuging, filter pressing or settling. Thecompound thus given as an example is apparently 1,3 dichlor, 2 methylpropane and has the following characteristics:

Boiling point 136 C. at 760 mm. pressure Specific gr 1.1375 at 15.5 C.Ref. index 1.4492 at 20 C.

3 at a temperature sufficiently high to effect solution of substantiallyall of the stock in the solvent and thereafter chilling the solution soformed to effect precipitation of wax therefrom. This wax is thereafterremoved by a method appropriate to its character; i. e., either bycentrifuging, filter pressing or settling.

In the practice of any process for removing wax from oil, it isnaturally desirable that a large pro- Application February 27, 1935,Serial No. 8,483

ed with a minimum amount of oil be obtained and that the avoidance ofprecipitation and separation with wax of oil ingredients of highviscosity index be avoided. While these three factors are intimatelyco-related, and cannot be considered entirely independently of eachother, it has been found that a more desirable co-ordination of resultscan be attained by the use of the present dewaxing solvent than ispossible by the use of any dewaxing solvent of the prior art.

The dewaxing solvent of the present invention has the additionaladvantage of having a comparatively low vapor pressure, although itsboiling point is sufficiently low to enable it to be effectively removedfrom the petroleum stock after completion of the dewaxing operations;

The following example illustrates the practice of the invention: 7

A Mid Continent distillate of the following specifications was dewaxedin accordance with the invention:

Gravity 23.8 A. P. I. Flash 455 F. Viscosity at 210 F Sec. S.U. Solidpoint 102 F. Color 4 N. P. A.

This was diluted with the 1,3 dichlor, 2 methyl propane described abovein the proportion of four parts of solvent to one part of oil and heatedto 100 F., at which temperature it was bright.

The mixture was chilled to 10 F. and filtered through canvas to effectseparation of wax. The dewaxed oil was washed with the 1,3 dichlor, 2methyl propane chilled to -10 F., using two parts of solvent to one partof oil, the wash liquid being added to the dewaxed oil solution.

The solvent was evaporated from oil and wax and an oil was obtainedhaving a solid point of --2 F. The yield was Oil 93.5% Wax 6.5%

Dewaxing a similar fraction by the conventional method using naphtha asa diluent and centrifugal separation gave the following yields:

Oil Wax 25% I claim:

1. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the oil content of the stockin 1,3 dichlor, 2 methyl propane and thereafter removing wax from thesolution at a temperature sufiiciently low to effect precipitation ofwax.

2. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the stock in 1,3 dichlor, 2

methyl propane at a temperature sufliciently high to efiect solution ofboth oil and wax in the solvent and thereafter chilling the solution toa temperature sufficiently lowto effect precipitation of wax andremoving precipitated wax from the oil solution.

3. The method of dewaxing petroleum stock which comprises selectivelyextracting. oil from the stock by dissolving the oil content of thestock in 1,3 dichlor, 2 methyl propane and thereafter removing'wax fromthe solution by filtration at a temperature sufliciently low to efiectprecipitation of wax.

. 4. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the oil content of the stockin 1,3 dichlor, 2 methyl propane and thereafter removing wax from thesolution by centrifugalforce at a temperature sufficiently low to effectprecipitation of wax.

5. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the oil content of the'-=stock in 1,3 dichlor, 2 methyl propane and thereafter removing'waxfrom the solution by cold settling at a temperature sufficiently low toeifect precipitation of wax.

6. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the stock in 1,3 dichlor, 2methyl propane at a temperature sufficiently high to effect solution ofboth oil and wax in the solvent and thereafter chilling the solution toa temperature sufficiently low to effect precipitation of wax andremoving precipitated wax from the oil solution by filtration.

'7. The method-of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the stock in 1,3 dichlor, 2methyl propane at a temperature sufiiciently high to effect solution ofboth oil and wax in the solvent and thereafter chilling the solution toa temperature sufiiciently low to efiect precipitation of wax andremoving precipitated wax from the oilsolution by centrifugal force.

8. The method of dewaxing petroleum stock which comprises selectivelyextracting oil from the stock by dissolving the stock in 1,3 dichlor, 2methyl propane at a temperature sufficiently high to effect solution ofboth oil and wax in the solvent and thereafter chilling the solution toa temperature sufficiently low to effect precipitation of wax andremoving precipitated wax from the oil solution by cold settling.

9. The method of dewaxing petroleum stock which comprises-selectivelyextracting oil from.

the stock by dissolving the oil content of the stock in dichlor butanehaving approximately the following properties:

Boiling point 136 C. at 760 mm. pressure Specific gravity 1.1375 at 155C.,

Boiling point 136 C. at 760 mm. pressure Specific gravity 1.1375 at 1550.,

and thereafter removing wax from the solution at a temperaturesufficiently low to efiect'precipitation of wax.

LEO D. JONES.

